The early biochemical events which result in lymphocyte stimulation by extracellular signals are being sought. These signals include the action of non-physiological agents, such as mitogenic lectins, and also soluble factors which transfer information between cells. The earliest enzymatic event detected thus far is the activation of membrane associated transmethylases. This is followed by increased calcium ion flux, activation of phospholipase A2, arachidonic acid release and increased activity in the lipoxygenase pathway. To facilitate these and other studies, we are also seeking to identify and fractionate subpopulations of lymphoid cells. In addition to our ongoing experiments, using specific lectins to recognize cell surface glycan differentiation markers, we are evaluating the use of neoglycoproteins and polysaccharides to identify specific carbohydrate receptors on subsets of lymphoid cells.